How are newborn screening tests done?

Newborn screening typically consists of a blood test and a hearing test. First, hospital staff fill out a newborn screening card with the infant’s vital information—name, sex, weight, date and time of birth—and the date and time of the blood collection. Part of the card consists of special absorbent paper used to collect the blood sample.1

Heel Stick Blood Test

After warming and careful sterilizing of the infant’s heel, blood is taken through a "heel stick." The absorbent portion of the screening card is then placed in contact with the blood drop. This procedure is repeated with a series of new drops of blood until all the printed circles on the card contain a blood sample. These blood samples are used to conduct the screening tests, which are done in carefully controlled high-volume clinical laboratories.

Hearing Test

Hospital staff typically use one of two methods for the hearing test. Both are quick (5 to 10 minutes) and safe.1

Otoacoustic (pronounced oh-toe-uh-KOO-stik) emissions (OAE). This test determines if certain parts of the infant’s ear respond to sound. A miniature earphone and microphone are placed in the ear, and sounds are played. If the infant has normal hearing, the microphone picks up an echo reflected back into the ear canal. Failure to detect an echo means there may be a loss of hearing.

Auditory (pronounced AW-di-tohr-ee) brain stem response (ABR). This test evaluates the auditory brain stem—the part of the auditory nerve that carries sound from the ear to the brain—and the brain’s response to sound. Miniature earphones are placed in the ear, and sounds are played. Electrodes (small, sticky electric conductors) are placed on the infant’s head to detect the brain’s response to the sounds. If the infant’s brain does not respond consistently to the sounds, there may be a hearing problem.

Pulse Oximetry (pronounced ox-EM-i-tree)

In some cases, hospital staff will perform pulse oximetry to measure how much oxygen is in the infant’s blood. Pulse oximetry is usually performed after the infant is 24 hours old. Hospital staff place a sensor on the infant’s skin for a couple of minutes, and the sensor measures the level of oxygen in the blood through the skin.

Low blood oxygen can indicate that a newborn has heart problems. Pulse oximetry can help identify infants with a condition called critical congenital (pronounced kuhn-JEN-i-tl) heart disease (CCHD).1 Annually, CCHD accounts for 24% of all infant deaths that are due to birth defects. This type of screening can identify infants who need to be seen by a heart specialist and receive lifesaving care.

Other Blood Tests

Some states require a second blood test that repeats the initial set of screenings.

The first screening is performed 24 to 48 hours after the infant is born, ideally before the infant leaves the hospital. For some conditions, the screening is not valid if the blood is taken before a newborn is 24 hours old.

The second screening is performed when the infant is 10 days to 2 weeks old to ensure that the child’s doctor has the most accurate results possible.